FISHERY RESEARCH
'
331
‘
the sh up to boiling point in water so that it _is just begin—
ning to be co”oked.
The esh may then be easily scraped
from off the backbone, without the backbone itself falling
to pieces.
A much more rapid and clean method which
may replace the older method, is merely to take X—ray »
photographs of the herring, when the vertebræ can be
counted on the negative (Plate 120).
'
.
The scale of the herring is well suited for
'
studying its growth
_
.
,
.
rate, for the yearly
.
«
-
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©
_
rings containing broad
'
_
,".
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and narrow bands, cor—
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;"
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responding to periods
,
_
-
;'
,
es_
offastandslowgrowth,
-
.
,r’
ate clearly marked out
.
,/'
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on it (Plate 120).
It
j ‘
,_/
.
—
4
‘
.
is known that the scale
_
.
,’
,"1_ .
4
_
grows in proportion at
._
'
'
‘
a
corresponding rate
.
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.
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to the body of the sh,
—
:/_
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_
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and from the distance
’…
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from the centre of the '
-Ç
.
_scale to the outer edge
..
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'
1
of each
earl
rin
can
Fm'.
showing.h0W the
be_calcîlateä thegsize gmwm
…
of the sh at the end
-
_
.
‘
'
_
of each year
(see Eig 62)- ‘
-'
-'
,
Examination of scales from large numbers Of herrmg dur—
-
ing the course of many yeàfs has_throW ”very mterestmg
'
light on the age composition of the shoals,
of sh.
It
f
may, for instance, be found thatin _one‘
year over
.
_
per cent. of the herring caughtWerele years_old,
the re—
.
m—ainder beingnioStly four, ve, seven ande1ght. The faCt